Process of treating lubricating oils with phenol at high temperatures



Patented Aug. 25, 1936 PATENT OFFICE PROCESS "OF TREATING LUBRICATING OILS WITH PHENOL ATURES Reginald K. Stratford,

AT HIGH TEMPER- Sarnia, Ontario, Canada,

assignor to Standard Oil Development Comp'any, a corporation of Delaware No Drawing. Application October 18, 1933, Serial No. 694,036

7 Claims.

The present invention relates to a process of treating lubricating oils with phenol and will be fully understood from the following description:

In my prior Patent 1,860,823, issued on May 31, 1932, a process for treating lubricating oils has been described, comprising agitating the oil with undiluted liquid phenol below the temperature at which the phenol becomes completely miscible with the oilfsettling, separating the oil layer from the phenol layer, and removing absorbed phenol from the oil layer. This treating process improves the gravity of the oil, reduces the sulfur content and also greatly improves the so-called viscosity index. The viscosity index is determined by the method described in the article entitled Viscosity variations of oils with temperatures by E. W. Dean and'G. H. B. Davis, in the Chemical and Metallurgical Engineering, October, 1929 number. This index is a measure of the ability of a lubricating oil to remain viscous at high temperatures; as well known oils lose rapidly their viscosity with increase in temperature. The oil with a high viscosity index will, however, lose its viscosity less rapidly than an oil with a low viscosity index when the temperature is increased. Good grade Pennsylvania lubricating oils have a viscosity index of 100. The present invention is an improvement of the process described in my above mentioned patent which allows obtaining especially good results with high viscosity and high viscosity index stocks. Some of the advantages of the process are, however, obtained with stocks which do not belong to this class.

Prior treatments with phenol have usually been carried out at temperatures above, say, 110 F. and below about 180 or 200 F. I have discovered that certain stocks, such as the high viscosity and viscosity index lubricating stocks above mentioned, are preferably treated at temperatures higher than about 220 F. Treating temperatures of 250 F. or even higher give very good results with such stocks. By treating a Mid-Continent steam refined stock at 180 F. it was only possible to obtain a viscosity index improvement to about 95. By increasing the treating temperature to over 200 F. it was possible to obtain a viscosity index of 100, this being accomplished with less phenol and giving a greater yield of treated oil than with a low temperature yield. The principal advantages of high temperature phenol treating are the followmg:

1. The viscosity index shows a more pronounced improvement.

2. The carbon residue, which is measured by the so-called Conradson carbon test, is materially decreased.

3. In many cases the viscosity at 210 F. of the treated oil is increased above that of the charge. 5 This phenomenon is quite extraordinary since in phenol treating processes the viscosity at 210 F. of the treated stock is usually lower than that of the untreated stock.

4. The settling time is reduced.

The reduction of the settling time is very important for the practical operation of the process, since an unduly long settling time will considerably reduce the capacity of the treating unit, as is easily understood. Very pronounced im- 15 provement of the viscosity index is also an important factor in my present process, especially in cases where this improvement can not be obtained by other means.

The present process is preferably carried out 20 with undiluted phenol, although small amounts of other organic solvents, whether selective or non-selective, may also be present. Thus, for

' example, other phenolic bodies, such as cresols, may be admixed with the phenol but only in such proportions as not to reduce the miscibility tem perature of the phenol with the oil too far, since too much reduction of the miscibility temperature will make a high temperature treatment impossible. The phenol may also contain extract removed from the oil in a prior treating step.

In some cases where the viscosity index of the stock is not sufliciently high to permit treating with phenol, the use of small quantities, such as per cent of water, alcohol, glycerol, or glycol, etc. in the phenol will make the treating successful. Such diluents lower the absorption power of the phenol so that equivalent yields can be obtained as with a lower temperature treat.

The details of the high temperature phenol treating operation are very similar to those described in my prior patent. The oil is agitated with the phenol and then allowed to settle until the separation of the two layers takes place. The phenol layer is then separated from the oil layer and the phenol is removed from both layers by means of distillation or other means. The treating may be carried out in batch or in continuous operation. The oil may also be given several batch treats, in which case the countercurrent principle is advantageously applied. The amount of phenol used may vary considerably, say from 50% to 300%.

The following example will illustrate my process:

A steam reduced Pennsylvania lubricating stock is given six 50% batch treats with phenol of 104 melting point at 200 F. and another sample of the same stock is similarly treated at 250 F. The settling times and the yields are the following:

Treating Treating Batch No. temperature temperature 40 minutes. 45 minutes hours minutes 45 hours 55 minutes 40 minutes. minutes minutes. 35 minutes minutes. 35 minutes Yield dephenolized oil 68% 32% The inspection data of the untreated and the treated oils are as follows:

Untreated Treated Treated oil at 200 F. at 250 F.

Gravity A. P. I 24. 7 27. 5 27. 7 Flash, F 590 610 Vis. Saybolt at F 1527 1188 1206 V15. Saybolt at 210 F. 230 201 243 Viscosity index 104 107 121 Pour/solidific. point, F. 30/25 30/25 40/35 Conradson, carbon, percent 3. 19 1.70 1.

250 F. than at 200 F. The yield of finished oil is lower for the 250 F. treating temperature than for 200 F. This, however, is more than counterbalanced by the other advantages obtained in the high temperature treat.

The present invention may be modified in different ways and is therefore not to be limited by the example given for illustration, but only by the following claims in which it is my intention to claim all novelty inherent in the invention.

What I claim is:

1. The process of treating hydrocarbon lubricating oil stock of high viscosity index, which comprises agitating the oil with a liquid phenol at a temperature above about 220 F. and below the temperature at which the phenol becomes completely miscible with the oil, separating the oil layer from the phenol layer, and removing absorbed phenol from the oil layer.

2. Process according to claim 1 in which the hydrocarbon lubricating oil is a high viscosity stock.

3. Process according to claim 1 in which the phenol contains a small amount of diluent.

4. Process according to claim 1 in which the treating is carried out at a temperature of about 250 F.

5. The process of treating hydrocarbon. lubricating oil stock of high viscosity index, which comprises agitating the oil with undiluted liquid phenol above a temperature of about 220 F. and below the temperature at which the phenol becomes completely miscible with the oil, separating the oil layer from the phenol layer, and removing absorbed phenol from the oil layer.

6. Process according to claim 5 in which the hydrocarbon lubricating oil is a high viscosity stock.

7. Process according to claim 5 in which the treating is carried out at a temperature of about 250 F.

REGINALD K. S'I'RA'IFORD. 

